Abstract
ABSTRACT: Autogenic controls have significant influence on deep-water fans and depositional lobes morphology. In this work, we aim to investigate autogenic controls on the topography and geometry of deep-water fans. The influence of the sediment concentration of turbidity currents on deep-water fans morphology was also investigated. From the repeatability of 3D physical modeling of turbidity currents, two series of ten experiments were made, one of high-density turbidity currents (HDTC) and another of low-density turbidity currents (LDTC). All other input parameters (discharge, sediment volumetric concentration and grain size median) were kept constant. Each deposit was analyzed from qualitative and quantitative approaches and statistical analysis. In each experimental series, the variability of the morphological parameters (length, width, L/W ratio, centroid, area, topography) of the simulated deep-water fans was observed. Depositional evolution of the HDTC fans was more complex, showing four evolutionary steps and characterized by the self-channelizing of the turbidity current, while LDTC fans neither present self-channelizing, nor evolutionary steps. High disparities on the geometrical parameters of the fans, as characterized by the elevated relative standard deviation, suggest that autogenic controls induced a stochastic morphological behaviour on the simulated fans of the two experimental series.
Highlights
Turbidity currents are powerful processes in deep-water fan systems in terms of volume of sandy sediments transported into ocean basins, and can generate large deposits with high potential for hydrocarbon reservoirs
Part one discusses the analogy with modern deep-water fans, part two deals with the influence of the sediment volumetric concentration on high-density turbidity currents (HDTC) and low-density turbidity currents (LDTC) fans morphology, and part three approaches the influence of the autogenic forces on the simulated deep-water fans morphology
This study led to the following conclusions: ■■ Autogenic controls influenced a stochastic morphological behaviour of the simulated fans of the two experimental series, as well in depositional element scale
Summary
Turbidity currents are powerful processes in deep-water fan systems in terms of volume of sandy sediments transported into ocean basins, and can generate large deposits with high potential for hydrocarbon reservoirs. Recent studies (Straub et al 2009, Hajek et al 2010, Jerolmack & Paola 2010, Prélat et al 2010, Wang et al 2011) on autogenic dynamics and allogenic controls have been focused on autogenic signatures within the sedimentary record. They intend to verify whether these records can be distinguished from allogenic signatures or mask some allogenic processes. A significant gap remains in the understanding of turbidity currents, because autogenic processes may form structures similar to allogenic processes
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